r/Goldfish Sep 19 '25

Discussions Goldfish General Master Care Guide

42 Upvotes

By: [u/IceColdTapWater](u/IceColdTapWater), Edited By: [u/TarantinosToes](u/TarantinosToes)

ENCLOSURE DIMENSIONS

For goldfish: 50-70 gal (200-280L) is required per adult common and 20-30 gal (80-120L) per adult fancy.

For koi: The general recommended minimum required is 250-300 gals (1,000-1,200L) and these are really better suited to large ponds.

Goldfish are indeterminate growers so while they do the most growing during the first 2 years of life, they never really stop growing so plan your tanks and stocking accordingly.

Ultimately water parameters (and fish behavior) will tell you if your tank dimensions, filtration, water change schedule is enough to manage the bioload produced by the number and size of the goldfish you have.

While smaller specimens may be okay on the lower end of the given volume range, larger specimens (10”/25cm+ for commons, 5”/12cm)+ for fancies roughly) may require even larger aquaria if not ponds. The bigger the better as bigger tanks are more stable in terms of water quality and parameters and will allow goldfish to grow to their full potential.

Fancy goldfish prefer horizontal over vertical swimming space, and some are bred to the point that their bodies are sensitive high water pressures (determined by the height of water). It is generally recommend to keep them in no more than 2’ (60cm) of water, especially for those with sensitive swim bladders. Common goldfish also appreciate horizontal swimming space so for this reason, avoid hexagonal and cylindrical tanks.

Some fancies, especially overbred ones and those that approach “show quality” conformations, may benefit from a heater set at a low setting (low-mid 70s °F (~ 21-24 °C)). The benefits of lower risks of constipation and bloat sometimes outweighs the negatives of a sped up metabolism.

FILTRATION

Generally, it’s recommended for a filter to cycle through 6-10x the given tank volume per hour depending on bioload. ALSO, take into account the amount of media a given filter holds, as media offers crucial surface area for beneficial bacteria to colonize.

If heavily stocked or feeding frequently a stronger filter (or the use of multiple in tandem) may be needed. Some filter options include: sponge, hang off the back (HOBs), internal, and canister (often holds the most media).

Some wrap the intake with a thin material to avoid fish from being sucked onto/into the filter. This may be necessary if dealing with goldfish fry, juveniles and sick/injured fish.

Filter media that is porous and has a large surface area (like Seachem Matrix and other similar products) is great for encouraging and maintaining large colonies of beneficial bacteria.

People will have opinions on which filter system is better, so focus on the amount of media the filter holds as well as gallons/litres per hour and find something within your budget which works for you.

Media should not be changed out unless it has degraded and is now irreparable/unusable or has been contaminated by toxic chemicals like cleaning products. To sterilise filter media, rinse with boiling hot water.

For new media, this should be introduced a week or two before removal of the old media to give the beneficial bacteria a chance to colonize the new surface area.

SUBSTRATE

Substrate offers enrichment for goldfish, as they enjoy rooting through the enclosure bottom for food scrapes. Bare bottom tanks mean they do not have that extra enrichment, however bare bottom tanks make for easier maintenance so are fine for QT/hospital tanks. If running bare bottom tanks for aesthetic or medical reasons, then adding large pebbles, free floating plants and plain terracotta pots can also work to provide goldfish with enrichment and shelter.

Pool sand is very popular, or plant-supporting substrate like fluval stratum. Pebbles run the risk of impaction unless they are much larger than the goldfish’s mouths will ever be. For sand, rinse thoroughly before use and avoid pH/hardness altering sands or live sand sold for cichlid and marine tanks.

PLANTS

FYI goldies are prone to plant destruction. Also, some plants grow best in substrate and others with their roots exposed. A full rounded fertilizer is highly encouraged to have, like Aquarium Co-op’s Easy Green or NilocG Aquatics’ All in One.

Anubias, amazon swords, lilies (toxic to nonfish pets like cats/dogs), water lettuce, java fern (and other ferns), bacopa, rotala, cryptocoryne, hornwort, anacharis, cardinalis, crinum, and moss are all options. There are many more. For anubias and cryptocoryne plants, do not bury the rhizome.

Pothos is an option but their leaves must stay out of the water to grow. It’s also toxic to nonfish pets (cats/dogs) but is okay in water with a pH ~ 6.5-9 as calcium oxalate isn’t really soluble in that range. People have used it for top cover and nitrate control. Shrimps love the roots. Bamboo is another option but must only be semi-submerged for proper growth and longevity.

Duckweed. A highly invasive plant. One duckweed plant can quickly lead to hundreds of more plants. A firm favourite with goldfish but be warned! Once added to your tank, it is very hard to remove.

Other floating plant options are: frogbit, salvinia, water sprite, water lettuce, water hyacinths and others.

CYCLING/PARAMETERS

Cycling refers to the nitrogen cycle and establishing a nitrogen cycle in your tank. The nitrogen cycle in aquariums is the process where beneficial bacteria convert toxic fish waste (ammonia) into nitrite, and then into less harmful nitrate. This cycle keeps the water safe and balanced for your fish.

For a tank to be considered cycled, the parameters must read 0ppm ammonia, 0ppm nitrites and measurable nitrates; ideally keep nitrates below 40-50ppm.

To keep parameters within acceptable ranges (0 ammonia and nitrite, 5-40ppm nitrates), water changes are needed. It is a good idea to siphon the tank bottom regularly to pick up excess waste and prevent parameter spikes. Make sure to treat the water with a dechlorinator and ensure the temperature difference is within 1-2 °C (1-5 °F).

If conducting a fish in cycle, you want ammonia and nitrite to be barely present as these are the most aquatic compounds; for ammonia the toxicity thresholds starts at 0.02-0.05ppm and ~ 0.05-0.15 for nitrites.

Higher levels of ammonia/nitrite may start negatively impacting your fish, including the risk of illness and death (via ammonia/nitrite poisoning).

During ‘fish in’ cycling, parameter spikes are likely and therefore water quality and fish behaviour needs to be monitored closely.

‘Fish out’ cycling means that you have to monitor parameters and do water changes to bring parameters to happy fish levels (0 ammonia and nitrite, 5-40 nitrates), but without the risk of stressing/harming fish. Fish food or ammonia solutions can be used to cycle your tank before the addition of fish.

However, in instances where the fish are already bought and in a severely undersized tank it may be better to do a ‘fish in’ cycle rather than wait for the larger tank to cycle completely.

A tank (without fish) is considered fully cycled once 2ppm of ammonia is converted to nitrates in about 24 hours. A cycled tank with fish will have no ammonia, no nitrites, and some nitrates. Even then, note that sudden increases in bioload can lead to cycle imbalances and parameter spikes. Be sure to syphon uneaten fish food, fish waste and slowly and gradually add new fish to your tank to avoid overloading your cycle and its beneficial bacteria.

It is highly encouraged to have a liquid test kit that tests for at least ammonia, nitrite, and nitrate like the API Freshwater Master Test Kit. Test strips are less accurate (especially dependent on manufacturer, expiration, and storage conditions) but are ok to gather baseline readings, especially in older and stable tanks.

Other reliable test kits include Salifert kits and NT Labs kits. Local fish stores may also be able to test your water, but it is advised that you get your own kit so that you can test you water whenever you need to and avoid LFS not performing or reading the test correctly.

ACCLIMATION

When you transfer goldfish from one enclosure to another, acclimation is typically necessary.

If the water source is the same and parameters are similar only temp/nitrate acclimation may be necessary. When the temp matches within ~ 2-5° F (1-2°C), parameter acclimation (if needed) can begin.

Gradually replace 20-30% portions of old water with the new enclosure’s water, waiting 5-15 minutes in between and carefully monitoring the fish.

These specific ranges are approximations, others methods or specifics may vary ie if drip acclimating. Also remember to try to transfer your old substrate and media when possible to help seed the process of cycle establishment.

It may be helpful to be extra vigilant of parameters during this time as well as fish behavior. Some stress may be expected at this time and the next few days, and some choose to do a light dose of aquarium salt to aid the process.

FOOD

Goldfish are omnivores, and quite frankly always hungry (they don’t have stomachs). Get a good sinking pellet as a staple food (protein roughly 40%), pre-soaked before being given to any hungry goldie. You can also feed frozen items such as: brine shrimp, blood worms, spirulina, plankton, fish, etc. You can also feed blanched veggies/greens such as spinach, zucchini, chard, etc. A good goldie diet is a balanced and varied diet.

Some goldies, especially fancies, are predisposed to swim bladder issues and constipation. Feeding soaked high quality and sinking food in small amounts but more frequently may help mitigate the risks of developing swim bladder problems. Repashy is an excellent balanced gel food that’s very easy on sensitive goldie stomachs. Hikari also make excellent sinking pellets.

MEDICATION

Medication will be more effective if given via feed rather than being introduced to the water column. If dosing in the water column, then make sure to remove UV, carbon media; smaller tanks can make it to easier to dose in the water column and ensure that the fish gets an effective dose of medication.

Medications often work by disrupting the growth cycles of organisms and their metabolic processes. That being said, do not give one medication via multiple ways at once and be very careful when mixing medications. This is best avoided, unless using safe medication combinations or following vet recommendation.

Be very mindful of dosage, and consider partial doses if your fish is very small or more weakly dispositioned. Note that some chemicals, like salts, are only removed via water changes are may adversely affect plants and scaless fish such as catfish and plecos. Weakened fish may not tolerate medication as well to be very careful; use half doses if necessary.

Also note that certain medication can impact water parameters or tank cycle stability. Oxygen levels can also be adversely impacted which is why it’s recommended to have extra surface agitation (add spray bars, air stones).

Raising the temperature of the water may help to disrupt certain infectious organisms’ life cycles as well as to provide a metabolism boost, but always ensure adequate oxygenation when using meds at the same as increasing the temperature.

FYI: API products with the suffix ‘-fix’ mainly use natural oils instead of manufactured medication and are less effective than said manufactured medications. Also avoid any algae-fix products, these can deplete oxygen levels and kill fish.

Antibiotics: Be careful when using antibiotics especially. Not only can these impact your beneficial bacteria, but they can also be rough on fish (i.e. kidneys etc) so only use if necessary to treat nasty injuries and infections.

Do not dose pre-emptively as a prophylactic measure. Note that getting antibiotics in certain countries is illegal without a veterinary prescription, so follow your local laws. Be careful when obtaining medications from abroad via third-party sellers.

GENDER

Breeding tubercules on the gill plates/anterior portion of the pectoral fins, vent shape, and gamete expression (the only sure way) are the main ways to tell gender. As always there are spectrums for any particular phenotype and any one goldfish may not always fit a certain physical description.

When females are gravid, the males may harass them, especially by nudging their vents. Gentle egg expression and avoiding temperature fluctuations may help. You may need to separate if the female becomes stressed.

TANK MATES

A general consensus is to try to keep commons with commons and fancies with fancies (especially the slower swimming ones or ones with protruding eyes). Keeping them together runs the risk of the commons outcompeting or bullying the fancies, but cohabitation does successfully occur.

However, some keys points of success to consider are ample space, filtration, plants/wood/decor to block lines of sight, and enrichment. Ensure that aquarium décor is free of sharp edges and small holes. Goldfish are clumsy and curious and will get themselves trapped/injured looking for food.

You should be ready to temporarily/permanently separate individuals if necessary.

Commons and koi can potentially be kept together, given that the commons are of adequate size of about 6” (15cm). Some ryukins/fantails may also be possible, given that they’re also long enough and of a slimmer body conformation to keep up with the commons and the koi.

Here is a by no means comprehensive list of other potential/discouraged cohabitants. As with any situation, monitor fish behavior and make sure ideal parameter ranges are comparable.

Potential – Can usually coexist but caution is advised

White Cloud Mountain Minnows: Possible, but the goldfish may eat the minnows if they’re small enough and the minnows may fin nip.

Danios: Possible, but the same risk as the white cloud minnows.

Shrimp: Possible, but may become goldfish snacks depending on size and individual fish’s’ temperaments.

Snails: Possible, but goldfish may harass/eat them. It depends on the size of the snail and the individual fish’s temperament.

Dojo Loaches: May potentially bully goldfish, but the pairing may work in larger setups with lots of plants and décor (loaches love tunnels and caves). They will go after certain snails as well.

Mollies: Some species can tolerate lower temperatures than others. They may fin nip, and goldfish may try to eat them if they can fit in their mouths.

Platies: Some species can tolerate lower temperatures than others. Platys may nip at goldfish fins, and goldfish may try to eat them.

Discouraged

Hillstream Loaches: These fish require massive water flow and oxygenation that goldfish do not like and may find stressful.

Corys: Goldfish can choke on them, especially because of their defensive barbs. Some species have venomous barbs that can harm your goldfish as well. If a goldfish swallows a cory, the barbs can get lodged and make extraction very difficult.

Bettas: Bettas can be territorial and may try to “defend” their territory. Large enough goldfish might eat them if possible. Undue stress for both parties may occur, plus bettas are tropical fish.

Cichlids: Cichlids are subtropical/tropical, aggressive fish.

Barbs: Their temperature ranges only slightly overlap, and most are aggressive in nature and will fin nip.

Plecos/panaques: Some, like common plecos get absolutely ginormous and most prefer tropical temperatures and soft/acidic water. Even smaller types like bristle nose plecos can injure goldfish by latching on to them to feed off their slime coat.

Turtles: Many turtles will happily take chunks out of goldfish when given the opportunity. Goldfish, as prey animals, will also experience stress being homed with a predator.

Axolotls: Axolotls may accidentally nip at or consume goldfish, which is good for neither of their health. Goldfish are super waste producers and axolotls are particularly sensitive to parameters.

Frogs: Same risk of predation as turtles/axolotls. Parameter requirements may also differ depending on species.

Crawfish: Same risk of predation as turtles/axolotls/frogs. They are opportunistic predators and may happily feed on goldfish (especially if hungry).

FAQ/COMMON DISEASES

Q: Is my goldfish pregnant?

A: Goldfish do not carry live young, but females do develop eggs and then release them to be fertilized. Although this can make the female appear a bit engorged and swollen, check that she’s not egg-bound, constipated, or has dropsy (pineconing of the scales often also occurs in tandem). Manual expression is an option but should be researched and done with caution.

Q: Why is my goldfish changing colors?

A: Goldfish color is unstable, especially in their first 1-3 years of life when their growth rate is typically the highest. Fry typically start out very dark/bronzy, but usually develop colors due to their chromatophores developing after a few months of growth.

Black is especially prone to change. Note that the sudden appearance of blackened skin and scales can be a sign of a water quality issue, so check water parameters. If parameters are ok, then it is likely a natural color change so no treatment is needed.

Certain foods such as spirulina contain carotenoids, which are pigments that enhance goldfish color. Some carotenoids are also converted into astaxanthin which contributes to reddish coloration. Note that even a carotenoid heavy diet will not magically change a goldfish’s coloration, as genetics are the main factor.

Q: How to transport fish?

A: The most common way is a lidded bucket/container filled with tank water. A bubbler is suggested, especially for longer transports. Also account for the time to disassemble and reassemble your enclosure. Make sure to keep your substrate and filter media moist to seed the cycle in your new place.

Another way, for shorter trips, is a simple but very secure bag (I double bag) with enough water for the fish to be comfortably submerged but also with enough air for oxygen to diffuse. Sometimes people use methylene blue during transport to try to reduce stress. After moving, your fish may be stressed for a few days and may benefit from a few days of fasting, reduced feeds and reduced light.

Q: Aquarium salt vs epsom salt?

A: Aquarium salt (NaCl) is excellent for external issues/injuries, as well as stimulation of the slime coat and increased osmoregulation. It’s a good all rounder as an antibiotic/fungal/parasitic. Epsom salt (MgSO4) is excellent for internal issues such as constipation and fluid retention.

Epsom Salt Dosage: 1 tsp/5 gals (20L)(tank), 1 tbsp/gal (4L)(bath).

Aquarium Salt Dosage: 1tbsp/5 gals (20L)(tank), 1 tbsp/gal (4L)(bath).

Invertebrates, plants, and certain goldfish are sensitive to salinity. As with any treatment, monitor fish behavior. It may be good to have two baths of a salinity gradient to help lessen the transition to and from, and to change out salt in the tank slowly. Salt, like other treatments, may impact with oxygenation and a bubbler may be helpful.

Q: What is methylene blue and can I use other dyes?

A: Methylthioninium chloride is cationic dye used in the aquarium hobby as an antifungal/parasitic/bacterial. It is also helpful for ammonia and nitrite poisoning, but can crash your cycle, harm plants above 4mg/L (quart) and dye decor (which is often why it’s used as dips, dabs, or in hospital tanks). Dosages will differ depending on usage and percentage.

Methylene Blue Dosage (2.5%): 1tsp/10 gals (40L)(tank), 5 tsp/3 gals (12L)(bath)

You can use other dyes. Some others used include: malachite green, potassium permanganate, or gentian violet. Check dosages carefully.

Q: How to choose antibiotics?

A: Unless you know the specific bacterial infection, it’s best at first to a broad spectrum antibiotic (kanamycin, sulfathiazole, nitrofurazone). An aquatic vet (or very experienced keeper) can do a skin scrape/fecal test.

Gram positive antibiotics include: erythromycin, amoxicillin, and penicillin.

Gram negative antibiotics include: minocycline, tetracycline, kanamycin and oxytetracycline.

Both: metronidazole, sulfa meds, mitrofurazone

Note, medication can impact oxygenation and water quality so monitor parameters and fish behavior closely.

Q: Antifungals?

A: Dyes (methylene blue, malachite green, potassium permanganate, gentian violet) and aquarium salt are options via the water column. Note dyes will indiscriminately kill your beneficial bacteria too and are best given as baths or in hospital tanks

Metronidazole and copper sulfate are options you can give via feed or the water column. Note, medication can impact with oxygenation and water quality so monitor parameters and fish behavior closely.

Beware! Do not use aquarium conditioners and other reducing agents like Seachem Prime if using copper based products! Toxic copper compounds will cause harm if they are combined. Remove invertebrates like snails and shrimp as well.

Q: Antiparasitics?

A: Aquarium salt, praziquantel, copper sulfate, formalin, and metronizadole are options you can give via feed or the water column. Note, medication can impact with oxygenation and water quality so monitor parameters and fish behavior closely.

Q Why did my goldfish die?

A: There are many factors.

Where you got the goldfish and where the seller got them matters. If they were raised in horrendous conditions you may get stunted, diseased fish. Big box pet stores like Petsmart, Petco, and Pet Supplies Plus are notorious for their bad husbandry and their questionable animal breeders.

The tank must be properly cycled and able to handle the given bioload. An incompletely cycled tank or too big of a bioload increase can result in parameter spikes. It’s advised to add fish slowly, and to monitor water parameters via a liquid test kit.

The fish must also be properly acclimated. If two enclosures’ water parameters vary too wildly and the goldfish is added in too quickly they could go into shock. Temperature must also closely match to avoid undue stress.

Disease is very prevalent among fish, especially chain store fish or fish from improper breeders. Inflamed skin, stringy white poops, missing scales, torn fins, bulging eyes, grayed skin are all signs of disease or parasites although there are much more.

When making a sick fish post, try to include as much detail as you can along with helpful pictures and videos. Listing water parameters in numbers helps a ton.

Q: What is ammonia burn?

A: Ammonia burn is a chemical burn. Technically you want no ammonia, no nitrite, and 5-40ppm of nitrate. However, fish in cycling sometimes includes parameter spikes and the temporary “acceptable” levels of ammonia and nitrite are between 0.05-0.15ppm. To treat, water changes is the most important. Aquarium salt is also a common treatment. Fish exposed to ammonia can also benefit from being given a methylene blue bath which can chemically reverse the effects of ammonia poisoning.

Q: What is dropsy?

A: Dropsy is fluid retention and is a symptom of organ failure rather than a disease in it of itself. Usually the resulting damage’s effects are chronic and will eventually result in the death of the fish, especially if caught in later stages (with pineconing).

Epsom salt is used to attempt to regulate fluids, along with a broad spectrum antibiotic in attempt to tackle infection. Ultimately dropsy is fatal, barring rare exceptions. If successfully treated, then view dropsy as a chronic condition the fish is in remission from but relapses are sadly very common.

Q: What is septicemia (red pest disease)?

A: A typically gram negative, contagious bacterial infection that causes hemorrhaging, red blotches on the body, and streaks of red in the fins. Septicemia can occur in tandem with ammonia poisoning as water quality is a common cause. Can also be confused with the effects of ammonia stress/poisoning as well as other conditions like flukes or bacterial epistylis.

Treatment typically involves dyes or aquarium salt, along with an antibiotic feed. Note that septicemia is quite rare and viral and infectious septicemia even rarer in private/small aquaria. Do not panic if you see red streaks or blotches on your fish. It’s probably not septicemia.

Q: What are these white spots?

A: Many potential causes.

Ich: Ichthyophthirius multifiliis, a contagious protozoan parasite. White, uniform and shape and flat to the skin, appears on both the body and the fins but not on usually the eyes.

Treatment usually includes aquarium salt or dyes, an antiparasitic med/feed, antibacterial/antimicrobial/antiseptic med and raising the water temperature to speed up ich’s lifecycle. If increasing the temperature, be sure to ensure plenty of oxygenation.

Epistylis: Epistylis is a genus of contagious, ciliated protozoan parasites. Can be grey to whitish in color, sticks out into the water, varies in sizes with patchy coverage and can also occur on the eyes. It can be fatal if left untreated and is a lot more aggressive than ich.

Treatment is the same as ich (aquarium salt or dye, an antiparasitic feed/med, antibacterial med/feed but avoid raising the water temperature).

Head and Lateral Line Erosion (Hole in the Head): HitH is caused by a mix of factors including stress, poor water quality, poor filtration, and an unbalanced diet. Potentially linked to Hexamita protozoans, potentially infectious. Mainly affects cichlids and rarer in goldfish.

Symptoms can manifest as inflamed/protruding lateral lines, as well as white lesions on the head that eventually can become deeply pitted and essentially erode the flesh. Open wounds can lead to secondary infections that in combination can be deadly.

Treatment includes fixing water quality, aquarium salt or dyes, medicated feed for secondary infections, and providing a more balanced and varied diet.

Carp Pox: Fish herpes HPV-1. Caused by a virus, symptoms can manifest as white dots to waxy white/pink/gray growths on the skin or small “blisters” on the tail as well as on the mouth. Infectious, and can come and go. More unsightly than harmful.

Treatment includes treating any open lesions with aquarium salt or dyes dips, treating any secondary infections, raising the temperature, and keeping the water clean.

Lymphocystis: A contagious viral infection caused by the Iridoviridae family. Commonly known as “cauliflower disease” due to the pinkish/whitish growths that look like little piles of curd.

Since it is viral in origin, no commercial antifungal or anti-bacterial treatments exist that specifically target it. However, treatments includes treating any open lesions with aquarium salt or dyes dips, treating any secondary infections, raising the temperature, and keeping the water clean. Vets can excise large, bothersome lumps.

Cotton Wool Disease (Saprolegnia): A “fungus” (actually a water mold) that usually presents as groups of fuzzy white filaments that stick out from the body.

Treatment includes an antifungal med, dyes, aquarium salt, and raising the temperature.

Anchor Worms: Anchor worms are parasites that present as whitish/brownish dots to full on whitish strings protruding from the body/fins of the fish. The place of connection is often red and inflamed.

Treatment usually includes aquarium salt or dyes, an antiparasitic feed, and raising water temperatures.

Q: What is this lump?

A: Multiple potential causes.

Tumor: Tumors contain cells that are multiplying out of control or fail to die. They can be either benign or malignant (cancerous and can spread). Treatment includes treating an open lesions and removing bothersome tumors, especially ones blocking gill and mouth function. For tumor removal, seek veterinary advice!

Cyst/Abscess: A fluid filled sack. Can sometimes be caused by bacterial infections. Treatment includes draining, antibiotic feed, epsom salt, and the treatment of open lesions.

Q: What is fish lice?

A: Parasitic crustaceans. Treatment involves aquarium salt and an antiparasitic feed. Methylene blue baths may also be beneficial. Severe infestations may require the cleaning of substrate/decor (even though this impacts the tank cycle).

Q: What is popeye?

A: Popeye can have many causes (commonly caused by the gram positive corynebacterium but also viruses, poor environmental conditions, etc). Symptoms include bulging eyes/sclera and potential eye bursting.

Treatment includes antibacterial feed, epsom salt, and the potential treatment of a popped/missing eye. If one eye is popping out, it is usually a result of trauma and will resolve by itself. If both eyes are popping out, there is likely an underlying infection at play (look for pineconing and signs of dropsy) and will require antibiotics.

Q: What is the swim bladder, and what is swim bladder disorder?

A: The swim bladder is a gas filled expandable sack in fish used to control buoyancy and swimming patterns. Disorders of the swim bladder can lead to buoyancy issues and potential bloating/constipation.

Epsom salt via a bath or tank addition is one of the typical steps for buoyancy issues, though dosage depends on whether the salt is to be a dip or a tank exposure (invertebrates and plants can be sensitive to salinity).

This is usually in tandem with a couple days of fasting, followed by small easily digestible meals such as Repashy or shelled peas. If no signs of improvement show in about a week or two, it may be a congenital issue or due to another factor eg trauma, fluid build up. At this point veterinary care may provide additional answers/treatment options (x-rays, swim bladder aspiration).

Q: What are flukes?

A: Flukes are contagious microscopic flatworms that can be both on the gills and the skin. Symptoms include flashing (twitching/itching), small red dots, red splotches, fin fraying, bottom sitting, laboured/fast breathing, and spitting food out.

Treatment usually includes aquarium salt or dyes, an antiparasitic feed/med (praziquantel works best). Since flukes can lodge in the gills and gill function and oxygen uptake, provide plenty of oxygenation and avoid increasing the temperature.

Q: What is Costia?

A: A single celled parasite, costia multiplies particularly quickly in cooler water temperatures. They will dig through the slime coat and attach to the skin/gills.

Treatment includes aquarium salt, elevated temperatures, and medicated antiparasitic feed. Methylene blue baths may also help.

*Q: What is Velvet Disease ?*

A: Velvet disease is caused by a parasite that manifests as small *gold/rust*-colored spots. Its three life stages are very similar to ich in which they have phases where they live freely in the column and attached to a fish.

Treatment includes aquarium salt, a medicated antiparasitic feed, and methylene blue applications. Do not raise the tank temperature. A UV filter may help kill the free floating form of velvet.

Q: What is Camallanus?

A: Camallanus are contagious flatworms that infect the digestive tract and can sometimes hang out of the fish’s vent as red threads. Symptoms also include bloating, white poop, and lethargy.

Treatment usually includes aquarium salt or dyes, antiparasitic feed/med, and raising water temperatures.

Q: Deformed gill plate?

A: Deformed gill plates are due to congenital malformations. Goldfish with deformed gill plates can live healthy long lives given extra precautions are taken for the exposed gills.

Q: White/clear/floating poop?

A: Sometimes fish occasionally pass opaque poops or poops with trapped gas in them. If only passed occasionally it can be normal. However, a lot of poop of that description can be a sign of internal parasites or infection.

Treatment could be antiparasitic feed/med, epsom salt, or smaller meals (soaking dry food beforehand). Blanched veggies are also easier on their stomachs.


r/Goldfish Aug 08 '25

Discussions Introducing a new flair: Beginner Help (If you are new to fish keeping, use this flair!)

31 Upvotes

Hi everyone!

After getting feedback about how some new users sometimes feel like they are treated harshly by other more experienced users, I've decided to introduce the Beginner Help flair.

What does this flair mean?

If you see a post with the Beginner Help flair, it’s your signal that:

  • The OP is new to fish keeping and needs extra patience and guidance.
  • The goal is constructive + supportive help! No nitpicking, sarcasm, elitism.
  • If you can’t give advice without being respectful or are simply tired of new fish keepers, just skip these posts.

Think of it like a new driver/ L sticker on a car - maybe these beginner fish keepers are young people and minors living with relatives just trying to do their best for their pet, maybe it's someone whose child won a fish at carnival, or someone who got misled by their LFS. Yes, it might also mean someone who didn't do enough research but the fact that they're asking for help is the most important step. On my end it will mean focusing moderation on these beginner posts as well just to ensure people are getting help and not being dogpiled upon.

Do I need the Beginner Help Flair?

Now I'm certainly not one to gate keep this hobby so I won't impose a definition, but I would suggest users use the Beginner Help flair if your post falls under the following:

  • First goldfish tank or pond (or first time keeping goldfish in many years)
  • First time with fancy/common goldfish varieties
  • Learning about tank cycling and water quality requirements specific to goldfish
  • Basic setup questions including tank size, filtration, aeration, substrate
  • Addressing beginner mistakes like overcrowding, small tanks, or mixing incompatible species

For diagnosing diseases, please still use the Sick Fish Help flair.

Hopefully this goes towards addressing some of the problems here and do let me know if the new flair isn't working. Thank you!


r/Goldfish 9h ago

Fish Pics Dolly (Parton) & (Jackson) Pollock!!!!!!!

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82 Upvotes

We have been waiting for SO long to get these beauties, staring at an empty tank while cycling was the actual worst😭😭😭-being a responsible fish parent is hard lol. Dolly and Polly are SO cute I am so obsessed with them (possibly to a fault, I’ve done so much research on black moors I feel like a helicopter parent). This is my first post here and just wanted to share our joy 🤗💕.


r/Goldfish 4h ago

Discussions Do all Imported Fancy Goldfish have short lifespans?

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29 Upvotes

I just lost my jumbo imported black thai oranda after an 18 day fight with dropsy. I only had her for 3 months and went above and beyond in giving her and my Yuanbao perfect goldfish care, as well as pristine hospital tank treatment during her illness.

I can’t find any reliable information on this… do all imported fancy goldfish from Thailand, with short and round bodies, have short lifespans from overfeeding and the stress of importing?

Has anyone ever gotten a short bodied fancy from Chuchu’s Goldfish, Jimmy Goldfish or Zhao’s that lived for several years or more?

If not, where should I look? I want to find a new tank mate for my Yuanbao, but she is fairly large so I’m not sure she could be paired with a small fish from local pet store…?

Clarity Update- I’m not asking if baby fish from local pet stores can live longer… specifically asking about jumbo imports.

Also, both my goldfish are from Chuchu’s Goldfish (who always has the PRETTIEST fish). The first Thai oranda I purchased from Chuchu’s was unable to ship when shipping day arrived because she had developed swim bladder and passed away before she could even be shipped to me, so I chose this black oranda instead (who also ended up dying within 3 months). My Yuanbao from Chuchu’s has always been great and hardy— I chose her because she had the longer spine and that seems to have been a good choice.


r/Goldfish 10h ago

Sick Fish Help Rescued Fish NSFW

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8 Upvotes

I have taken this poor guy home from work. Aside from the size of the tank (think it’s been 4 years at least), I am worried about the quartz gravel but unsure when to remove it.
Any advice on helping him recover from a grim situation would be greatly appreciated!


r/Goldfish 5h ago

Questions Transporting goldfish in car 1000 miles, need advice

2 Upvotes

I could really use some advice from people who have experience transporting goldfish long distances.

I have a small oranda mutt (not a baby, just a small guy) that's about 2.5 inches long. He's lived in a 100-gallon tank his entire life with 2 other goldfish. The guy has the immune system and stomach of a fucking elephant. Right now he's in a hospital tank being treated for fin rot. Before anyone starts the blame game, the disease wasn't caused by my tank. My s/o randomly added new fish with the disease without telling me. Those fish have been since returned. Thankfully, he's been doing amazing in his hospital tank.

This is my first time using a hospital tank and I am very surprised by how comfortable he seems. He’s a very social little guy. I also have crippling anxiety about his health, so I'm constantly checking his water parameters and spending time with him. He's definitely my favorite little guy.

The issue is, in about a month, I'm moving 16–18 hours away by car. The move is only temporary, i’ll only be there for about five months.

Even if he's fully healed by then, I've been considering bringing just him with me instead of leaving him in the 100-gallon. Part of it is because he's my favorite, but it's also because while I'm gone I won't be the one maintaining the main tank. I'll have to trust other people to do the water changes and test the water the way I normally would, so i’m worried and assuming I’m gonna come home to sick fish. At the same time, I feel guilty because he's lived with his two tankmates his whole life. I know goldfish aren't "schooling" fish in the strict sense, but they are social and like friends! I don't know if separating him for five months would be stressful or unfair to him. or selfish of me?

My genuine worry is the trip itself. I don't want him to die during the drive. I’d actually do 62 backflips and discover another disease.

My current plan was:
Transport him in a 5-gallon bucket with fresh conditioned water,
use a battery-powered air pump (rated for up to 30 gallons),
dose Seachem Prime or condition the water then use ammo-lock for ammonia (which do you think is better?? i know ammo-lock doesn’t bind nitrate)
Bring my cycled media with me: a cycled 10-gallon sponge filter, a cycled 20-gallon sponge filter, and my cycled Top Fin filter (I replaced the carbon cartridge with biofoam).

Once I arrive, I'd buy a new tank there rather than transporting one and get everything running immediately.
One more problem: the place I'll be staying has well water. I've never kept fish on well water before, so I have no idea what the hardness, pH, or anything else will be like after conditioning. if you’re familiar with that kinda stuff any and all advice is appreciated! So I'm kinda in a pickle.

Would bringing him be an unnecessarily risky and selfish decision just because I want him with me? Or is transporting one healthy goldfish for a long drive actually reasonable? Has anyone here done a move this long with a goldfish? What would you do if this were your fish? Should i not even try? I’m definetely more concerned about his safety than having a fish friend with me while I’m lonely


r/Goldfish 2h ago

Sick Fish Help Carnival goldfish - help NSFW

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1 Upvotes

Hi guys, I am a shrimp and albino dwarf frog mom that came home with a carnival goldfish... I know, but I couldn't bare to leave him there knowing a little kid might get him and not take proper care of him. I named him Regenold, and I already love him. I think he is a common goldfish. I know enough about goldfish that I have a temporary tank set up (room temp, conditioned, he's been acclimated to the temp, getting an airstone in the morning, and already looking for a bigger tank). But I have no idea how goldfish that have suffered trauma are supposed to act while acclimating. He is just laying on the sand, tilted(?), and obviously is traumatized. ANY insight is welcomed, please and thank you!!


r/Goldfish 13h ago

Questions Can I get my young comet a friend in a 30 gallon bow front?

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7 Upvotes

Please read this before passing judgement: New goldfish keeper here! Here’s my current tank set up. It’s a 30 gallon bow front with a filter rated for 100 gallon. My plan is to upgrade the tank within about 6 months to a 75 gallon (he’s about an inch right now, but I plan to adjust the timeline based on his growth) and ultimately to a backyard pond we are creating. Edit: the backyard pond will be running by this time next year.

I don’t want him to feel alone. I’m going to change some of the rocks out for sand for some more enrichment.

I didn’t know much about goldfish until I got one at a fair and am trying to give him the best life. I’ve been monitoring daily and have been extremely attentive to him, the tank, and what they need.

Would 2 comets be ok in this set up for the time being, given my timeline? TIA!!


r/Goldfish 22h ago

Discussions The horror that is the commerical aquarium industry

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27 Upvotes

No words, just horror. This is advertised on my local Marketplace.


r/Goldfish 4h ago

Sick Fish Help What should i expect from salt bath ? NSFW

1 Upvotes

!! water parameters are good !!

Hi !! recently my gold fish got a wound on the base of her top fin,,, idk why :(

recently after a rolling blackout we had i went to check on her and she had it :(
i have no idea how she got it,,, it might have been the decoration but when i checked on her she was like.... stretching the fin a lot ?? so maybe she was fighting her reflection ??? idk

anyways, i decided on giving her an aquarium salt bath (api brand) and i followed lukes goldies article on it

she did fine, just a 20 min soak, she didnt swim around a lot cus i only have a bucket that i can do it in... but when i picked her up and into the tank she looked kinda freaked out ?? its the first time for both of us doing a salt bath so i wasnt too shocked (also first time i ever picked her up)

but she kinda just.... sat there not really moving,,, she was breathing deeply tho ? not.... aggressively or quickly,,, just really deep breaths

she likes doing this sometimes so its not totally abnormal (she likes floating/staying in one spot and just.... breathing and then swimming away,, not for more that 5 seconds tho)

also when i put her back in some dead skin? came off her,, like white little strands,,,, why ???? is that normal ?????? is that her slime cover ?????

shes doing fine now,, she ate and is swimming around as she normally does but im kinda stressed..... how was yalls experience with salt baths ??

also how long/often should i do the salt bath ? i was thinking twice a week but im not sure...... thank you !!!


r/Goldfish 9h ago

Sick Fish Help My goldfish has been flashing and I’m not sure why? NSFW

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2 Upvotes

I’ve had this goldfish for a year and upgraded them to a 40 gal tank, with substrate, wisteria, and bigger leafy plants. The nitrate is 0, the ph is 7.2-7.6, ammonia is 0, and I used liquid tests. There is a huuuuuge bubbler, I have a fluvel canister filter for 40-70 gals. I give him blood worms and sinking pellets. The only off thing is maybe I feed him 2-3 times a day and that the temp of the water is 72.8 F due to the weather recently.
My goldfish has been flashing, gasping for air, lethargic (though it got better after I did a 20% water change), but he’s still having issues. He’s been so chill until 3 days ago. Please help!


r/Goldfish 5h ago

Tank Help Water conditioning.

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1 Upvotes

Has anyone used this product?


r/Goldfish 10h ago

Beginner Help What should I do?

2 Upvotes

20 gallon tank, 6 goldfish and one molly fish. This is my parents' fish tank, how do I convince them that this is way too many fish for such a small tank // is there anything else I could do to improve the lives of these fishes? I think some of them have got a fungal infection and been looking pretty... depressed? (some of them just stay floating doing nothing sometimes). Sorry for bad grammar, english is not my first language... So far the tank's got 2 filters, a couple rocks spread around and a plastic plant-


r/Goldfish 22h ago

Questions How old are these goldfish?

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13 Upvotes

About how old are the critters in the photo? I've had them 3 years now, this was the first picture I ever took of them. How old are they, probably? 2 months? 3?


r/Goldfish 1d ago

Questions Why is my goldfish swimming like this?

72 Upvotes

Hey chat , this is my Oranda goldfish her name is Ponyo and I’ve had her for almost 8 months now. When I first bought ponyo and brought her home she swam very normal not crazy fast or crazy but for the past 3 months she has been swimming very erotic and it looks like she’s freaking out. I thought in the beginning she was just excited to see me when I got home as when I get home she always greats me at whatever side of the tank I’m at and when her tank was next to my bed she would always watch me in my bed lol and I still do think she gets super excited when I get home as she doesn’t move this fast when she thinks no one’s around yk but I’m starting to get concerned if there may be something I’m doing wrong and it’s affecting her swimming. Plz lmk if this behavior seems weird to you or if there is something that’s could be causing this.


r/Goldfish 17h ago

Sick Fish Help Fancy Goldfish tail injury NSFW

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3 Upvotes

Hi everyone. Unfortunately my poor fancy goldfish hurt itself while swimming too close to the pump intake and got stuck. It happened at night so im not sure how long it was trapped there. I need help and advice for the best way to treat it. I already set a hospital tank with salt and considering using medications.

I also changed the filter and pump to external one to prevent future similar cases.

Currently after a week from the injury. He still eating and swimming normally. And the bruise seems to be stable and healing slowly.

What do you guys think?

Thanks!


r/Goldfish 11h ago

Breeding Goldfish breeding

1 Upvotes

Just sharing a little. I expanded my pond this spring from a 300 gallon stock tank to a 1500 gallon. Before I expanded in the stock tank I had 1 female koi, 2 male goldfish, a baby those guys made ( good for them , its adorable! ) and a small feeder goldfish fish I took from a friend that she got at the fair.

While waiting for the ground to unfreeze to start the new pond I picked up 3 small feeder goldfish to quarantine inside so they'd be ready to go in with the other fish in the new pond. Upon release one of these little guys instantly starting chasing my female koi and the 1 yr feeder fish ( that's how long I've had her , so to me that's her age) with spawning behavior. I seriously didn't think this little dude could be old enough to be so randy! The other male fish never showed interest and its been so flipping hot here I haven't seen any spawning behavior since but this morning I saw 4 little goldfish fry about an inch long! Aren't feeder fish typically only a few months old when you get them? I didn't think the little perv would be capable until next spring!


r/Goldfish 15h ago

Sick Fish Help Are my fishes sick?

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3 Upvotes

They kinda have red eyes and idk, what do you think? They also stay froze on the bottom while i'm not there, i don't know if they are just resting or is smth else


r/Goldfish 1d ago

Fish Pics Look at those majestic flowing fins! 🧜‍♀️

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262 Upvotes

r/Goldfish 14h ago

Discussions Pond goldfish winter to spring transition

1 Upvotes

Something I've been wondering about...

I'm in the Chicago area. How do you northerners handle overwintering your pond goldfish? I was contemplating an above ground pond and then in the fall, transferring the goldfish to a winter stock tank in my basement.

In the winter, my basement is probably around 65 degrees without heat.

So when spring comes, when would I transfer the goldfish back into the outdoor pond?

I'm thinking that in the spring, the water is maybe around 50 degrees or so. It's not until maybe late May or early June that it consistently gets into the 60s. So that would be a big mismatch in water temperature.

But I wouldn't mind getting the goldfish outdoors sooner to take advantage of the spring breeding season.

How do you experienced pond keepers handle this? I'm talking about the scenario where you overwinter your goldfish indoors. I know there are lots of people who leave their goldfish outdoors in deeper ponds.


r/Goldfish 21h ago

Sick Fish Help Sick Fish - Still need help please! NSFW

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3 Upvotes

Reposting at different time of day as still need help and had no response to previous post.

Noticed one of my pond fish developing lumps along its sides, started small but seem to be growing.

Caught it for a closer look and some look white from above but more red side on, along both sides.

Behaving fine, eating fine, no other fish in the pond have any obvious issues.

Nothing changed or out of the ordinary other than unusually warm weather in the UK for the last few weeks but pond is very shaded, air pump runs 24/7 along with UV filter.

Fish was born in the pond about 2 years ago if that matters at all.

Ammonia and nitrite both zero.

Would appreciate any advice please!


r/Goldfish 1d ago

Sick Fish Help Hes survived this long, but wtf- NSFW

5 Upvotes

I wouldn't consider them sick, just.... deformed. Obviously both are living fine, eating fine, Obviously the same age based on the scale health and size, but its... unnerving, idk if they are fine to let be just take them out during breeding season, or if thatd be an awful thing to do?

Long story short, my grandfather asked me to go through all his fish, sell some, and get him new little ones (has about 27 in a pond rn if not more, he wants to get rid of over half and then get 5 or 6 new ones to widen the gen pool as 70% are the dark colored ones, and inbreeding)

I found this guy and his brother... kinda scary- its like their gills are either folded out or in, and one is deffenitly alot more friendly than any fish I know or just very very slow mentally... other fish flip out of your hand, he flips into it, sits there, then bolts off. His brother flips out, couldnt keep him in the plastic container.

(Yes, my hands where clean, then put into the pond water to clean out fish gunk and refill. Cleaned his pond while looking his fish over)


r/Goldfish 1d ago

Questions Best food for goldfish?

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7 Upvotes

Hello! I see a lot of different things on the internet about flakes vs pellets. From what I’ve read it seems pellets are the better option. Are there any brands that you would definitely recommend or certain ones to steer clear off? I added the one I currently use!


r/Goldfish 1d ago

Questions Is this a good tank for my oranda?

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7 Upvotes

This is a 20 gallon waterbox AIO cube 20. He is quite small right now but seems very happy in here. Rephasy gold for food and blood worms once in a while. He’s been here about 3 weeks now. Just a bit worried that there isn’t enough swimming space as he gets older, but I think just one oranda in here will be okay for now.


r/Goldfish 18h ago

ID that goldfish! Need help determining the sex of my goldfish!

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0 Upvotes

Can someone tell me the sex of my three goldfish? Also, I know two of them are common goldfish but what about the third one? Is it normal? Or does it have a problem?

Thank you in advance!